1. Field of Invention
This invention relates to the chromatographic analysis of gaseous matter and more particularly to the processing of data obtained by chromatographic analysis.
2. Description of Prior Art
It is well known in the art to analyze gaseous matter by driving a sample of the gaseous matter through a material which delays the passage of the constituents of the matter in accordance with their molecular masses so that the constituents exhaust from the material in increasing order of molecular mass. For some gaseous matters, for example natural gas, it is known to provide two "columns" or materials which are put in turn in circuit to separate, on one hand, the methane from the other light gases and, on the other hand, the C.sub.2 to C.sub.4 and possibly the C.sub.5 hydrocarbons.
Apparatus for chromatographic analysis conventionally includes a detector, downstream of said material, sensitive to the passage of constituents therethrough, and which generates a signal varying in intensity in direct dependence upon the intensity of constituent flow through the detector. Such a chromatographic analysis apparatus is, hereinafter, referred to as "analysis apparatus of the type defined".
In conventional chromatographic analysis, the output from the detector is linked to a graph writing means, the intensity of the signal dictates the displacement of the graph writing means from a base line and, by traversing a graph recording medium at constant speed in a direction at right angles to the graph writing means, a representation of constituent intensity with respect to time is obtained with the different constituents in their order of exhaust through the detector. Thus, the result of a conventional chromatographic analysis is a graph comprising various peaks, each corresponding to a constituent of the gaseous matter, and the height of each peak above the base line reading is a function of the concentration of that particular constituent.
The interpretation of a chromatographic analysis in graph form as described above requires a series of manual operations as follows:
(a) Identification of each constituent, achieved by measuring the "time" distance between each peak and a "start" point on the graph indicative of a point in time before the gaseous matter was first subjected to the separating material. PA0 (b) Measurement of the height of each peak. PA0 (c) Assignment of each measured height of a calibration co-efficient corresponding to the nature of the constituent. PA0 (d) Calculation of the quantity or percentage of each constituent according to the signal (conventionally an analogue signal) provided by the detector. PA0 (e) Recordal of the values obtained for each, or selected, constituents.
The above procedure involves a relatively delicate and time consuming operation and requires specialized skill in the interpretation and calculation from the graphic display.